1. Field of the Invention
This invention relates to an information reproducing apparatus such as a digital audio tape recorder (hereafter called a DAT), a video tape recorder (hereafter called a VTR), and a compact disk player (hereafter called a CD player), which reproduces information recorded in tracks formed on a recording medium, and more specifically to a tracking control system used to control the position of a reproducing head relative to a track.
2. Description of the Prior Art
In a rotary head type DAT, parallel tracks are formed diagonally on a magnetic tape, and at a prescribed position on each track an ATF (automatic track finding) signal is recorded which is used to secure tracking of the reproducing head during reproduction (an operation to control a reproducing head to keep running on the center of a track is called "tracking"). A system in which the ATF signal is used to secure tracking is disclosed in "SERVO TECHNOLOGY OF R-DAT" AKIHIKO HITOMI et al, IEEE Transactions on Consumer Electronics, Vol, CE-32, No. 3, August 1986, PP425 to 431.
The ATF signal basically consists of pilot signals for detecting by crosstalk a relative position of the head to a track and a synchronizing signal for sampling and holding the pilot signals. More specifically, in any three successive tracks, providing that a head is scanning the center track of the three tracks a pilot signal recorded on one side track of the three tracks and a pilot signal recorded on the other side track of the three tracks are positioned to be shifted from each other in the track scanning direction so that they are reproduced by the head at different timings from each other. That is, one of the two pilot signals is reproduced earlier, and the other later. Note that the gap length of the head is larger than the width of each track so that the two pilot signals on the two side tracks adjacent to the center track are reproduced as crosstalk signals. A synchronizing signal recorded on the center track is positioned to overlap the earlier reproduced pilot signal in the head scanning direction.
However, since this system uses two sample/hold circuits and a subtracter, the size of the circuitry becomes large.